Start accepting Executors instead of Handlers.

After discussion in API council, our new best-practices are to have
developers provide an Executor to dispatch callbacks/listeners on,
instead of the previous guidance of using a Handler.

Define Context.getMainExecutor() to easily obtain an Executor
associated with the main thread of application.  This allows new
APIs to require a @NonNull Executor.  Also define a new
@CallbackExecutor auto-doc annotation that explains background and
points developers at new Context method above.

Test: cts-tradefed run commandAndExit cts-dev -m CtsContentTestCases -t android.content.cts.ContextTest#testMainLooper
Test: cts-tradefed run commandAndExit cts-dev -m CtsContentTestCases -t android.content.cts.ContextTest#testMainExecutor
Bug: 70348426
Change-Id: I536892bcd80fcfba1bb1ddf67648c08a26d7ddd2

1 files changed, 7 insertions, 1 deletions

diff --git a/core/java/android/content/ContextWrapper.java b/core/java/android/content/ContextWrapper.java
index 85acdc6b8101..67de4fe6bc4b 100644
--- a/core/java/android/content/ContextWrapper.java
+++ b/core/java/android/content/ContextWrapper.java
@@ -45,6 +45,7 @@ import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
+import java.util.concurrent.Executor;
 
 /**
  * Proxying implementation of Context that simply delegates all of its calls to
@@ -103,7 +104,12 @@ public class ContextWrapper extends Context {
     public Looper getMainLooper() {
         return mBase.getMainLooper();
     }
-    
+
+    @Override
+    public Executor getMainExecutor() {
+        return mBase.getMainExecutor();
+    }
+
     @Override
     public Context getApplicationContext() {
         return mBase.getApplicationContext();